A novel approach to produce soy protein isolate: Direct enzymatic hydrolysis of high-temperature soybean meal using proteinase produced by microbial solid-state fermentation

This study proposed a novel extraction method for soy protein isolate, which involved solid-state fermentation of high-temperature soybean meal. The proteinases secreted by microorganisms acted on the high-temperature soybean meal, making the SPI easier to extract. The study concludes that Bacillus amyloliquefaciens subsp. plantarum CICC 10265 could be used for solid-state fermentation of soybean meal, and the fermentation effect was good, with a yield of 41.91 % for SPI. Compared to the direct extraction of SPI from high-temperature soybean meal, the yield had increased by 130.19 %. Meanwhile, we also conducted research on the losses during the SPI extraction process. Through experiments, the study identified the patterns of protease activity changes and microbial colony growth during solid-state fermentation of soybean meal by Bacillus amyloliquefaciens subsp. plantarum CICC 10265. It was concluded that extracting SPI after 8 h of fermentation is more suitable. The experimental results indicated that the total amino acid content of SPI extracted from fermented soybean meal was 2.1 % higher compared to SPI extracted from low-temperature soybean meal. The extracted SPI also met the microbial standards.